Phylloxera was a vine louse that nearly destroyed all the vineyards around the world. France decided to take American vines and make French wines. They did not know the American vines that formed a resistance to the louse were carrying phylloxera. The old world vineyards were vulnerable and the louse who feeds on the roots of the vine destroyed a third of the worlds vines beginning in 1865. It was the greatest threat to wine production in history.
Thomas Volney Munson, The Grape Man of Texas, Munson found and sent specific disease-resistant grapevine cuttings to France, where farmers grafted their grapevines to the Texas roots, binding the two together, and crossed them with local plants. The tactics stemmed the tide of phylloxera and saved a range of delicate French grape varieties, including cabernet, merlot, pinot noir, and chardonnay. Even now, 135 years later, France grows wine grapes rooted on the descendants of Texas native plants.